1. Field of the Invention
The present invention generally relates to sphygmomanometers and, more particularly, to a sphygmomanometer gauge for indicating systolic and diastolic blood pressures. Still more particularly, the present invention relates to a method of indicating actual systolic and diastolic blood pressure readings during the blood pressure measurement for subsequent leisurely recordation and, yet more particularly, to a method of comparing actual systolic and diastolic blood pressure readings with predetermined medically-established pressure norms, as preset on the gauge.
2. Description of the Prior Art
A sphygmomanometer is a clinical apparatus for measuring the blood pressure. It comprises an inflatable rubber cuff which is wrapped around the upper arm of a patient. The cuff is connected by rubber tubing to a resilient hand bulb and is inflated by repetitively squeezing the bulb. A pressure-indicating manometer device or pressure gauge has a pressure-calibrated dial and a pressure needle, which is movable over the latter. The needle is operatively connected by a rubber tubing to the cuff, and is movable in response to changes in air pressure in the cuff. A manually operable bleeder valve is provided to slowly bleed air from the inflated cuff.
In use, sufficient pressurized air is pumped into the rubber cuff until the inflated cuff tightens sufficiently to occlude the brachial artery in the upper arm, i.e., stop the blood flow therein. A stethescope is applied over the artery below the cuff, and air is gradually allowed to escape through the bleeder valve from the cuff until a pulsing rush of blood can be heard. The pressure needle of the gauge at this point indicates the systolic pressure or the highest pressure in the arteries during contraction of the heart.
As deflation of the cuff continues, the air pressure within the cuff falls, and the needle successively indicates lower and still lower pressure readings. The diastolic pressure, or lowest pressure in the artery during diastole, or relaxation of the heart muscle between beats, is indicated by the needle on the dial when the last sound of the disappearing pulse is heard, i.e., when the rush of blood becomes inaudible. Upon further deflation of the cuff, the needle returns from its two previous measurement positions to its starting position. The normal systolic reading of an adult varies from 110 to 130 or 140 mm Hg. Normal diastolic readings vary from 60 to 90 mm Hg.
It is often difficult for an individual taking his own blood pressure to accurately read and note the systolic and diastolic blood pressures during the blood pressure measurement due to the fact that the individual must simultaneously regulate the air bleeder valve, carefully observe the pressure needle as it quickly moves over the dial, and listen to the sounds of the pulses through the stethescope. Moreover, even skilled personnel, who are trained in the art of taking blood pressure measurements, must either make a mental or very rapid written note of the systolic pressure reading at the appropriate time before the time approaches when the diastolic pressure must be read.
In order to eliminate the drawbacks involved in reliance upon a faulty memory and/or in making very hasty written, and possibly illegible, notes of the systolic and diastolic blood pressure readings, the prior art has proposed automatically-operated sphygmomanometer gauges which have two recording needles in addition to the main pressure needle. The main pressure needle, according to one proposal, automatically carries the two recording needles over the dial until the user decides to manually lock the respective recording needles in position. The prior art has also proposed a pair of recording needles which are moved automatically in response to pressure and electrical pulses and are locked automatically in their measured positions by a rachet-pawl-solenoid. Examples of such automatically-operated sphygmomanometer gauges can be had by reference to U.S. Pat. Nos. 3,901,217 and 3,056,401.
However, such automatically-operated gauges have not proven altogether satisfactory, inasmuch as the gauges require a considerable number of parts, are complex in construction, are expensive to manufacture, are cumbersome and are not altogether reliable or accurate. Moreover, all of the known automatically-operated sphygmomanometer gauges which separately record systolic and diastolic blood pressures utilize a pair of recording needles, each of which only records a single valve of blood pressure. It is highly desirable for a consumer-type user, as opposed to highly trained medical personnel, to be readily informed of a range of values of systolic and diastolic blood pressures, either in advance of or during the blood pressure measurement.